Control device



. May l2, 1942. E. H. AYERs 2,282,844

-CONTROL DEVICE Filed April 18, 1941 Inventor: :Ed af -LAHer'S,

His Attorneg.

Patented May 12, 1942 CONTROL DEVICE Edgar H. Ayers, Schenectady, N. Y., assignor to General Electric' Company, a corporation of New York Application April 18, 1941, Serial No. 389,183

9 claims. (c1. 20o-s3) My invention relates to control devices, more particularly to temperature 'responsive control devices such as used in refrigerators, and has for its object a simple, reliable and inexpensive device of this character provided with means for adjusting the temperature of operation.

In carrying out my invention in one form as applied to a temperature control device for electric refrigerators, I provide a control operating e arm which -is actuated by a pressure responsive device and' which is provided with a loading spring for opposing the pressure responsive device, together with means for changingthe point of application of the loading spring force to the operating arm thereby to give the loading spring a leverage advantage over the pressure responsive device. Thus an increased temperature is required to cause the pressure responsive device to move the actuating arm, which increased temperature may be utilized to defrost the refrigerator. For a more complete understanding of my invention, reference should be had tothe accompanying drawing, Fig, 1 of which is a planview with the casing in section of a control device embodying my invention; Fig. 2 is a view similar to Fig. 1 but with the device adjusted for defrosting operation; Fig. 3 is an elevation view of the operating mechanism without the enclosing casing; while Fig. 4 is a fragmentary 'view in perspective of the device with certain parts simplied for clarity.

Referring to the drawing, I have'shown my invention in one form as applied to'a temperature responsive device for controlling an elecn tube and container Il) form a sealed chamber or system in which is contained an expansible uid, such as methyl chloride. The opposite wall I2 of the container I is flexible so that its center moves in and out, or up and down as seen in Fig. 1, in response to changes in the fluid pressure in the container. Attached to the center of this Wall or diaphragm I2 is a pin I3 which is moved with the diaphragm and bears on an operating arm I4 which 1 the pin actuates to control the engagement and disengagement of a pair of electric contacts I5 and I6.

This operating mechanism is mounted on an electrically insulating support I'I, preferably made of a moulded compound, to which on each side is secured two metal supporting plates orV brackets I8 and I9 extending in parallel relation with each other and downward, as the device is viewed in Figs. 1 and 2. At the lower ends, these two arms are secured together to form a frame by a cross portion 20.

Laterally extending stiffening flanges 2I and 22 are provided on the operating arm I4 along opposite edges for nearly its entire length. These flanges form guides for a shorter intermediate adjustment member 23 which is also anged and has one end 24 held in position on the operating member between the flanges of the latter while its other right-hand end projects somewhat beyond the end of the operating arm. At its right-hand end the arm I4 is provided with a `pair of vlaterally extending projections 25 and 26 which extend through apertures provided for them in the supporting plates I8 and I9 and are pivoted in these apertures so as to define a pivot axis for the arm I4. Normally the intermediate vmember lies in lengthwise engagement with the operating arm as shown in Fig. 1.

The operating arm I4 is biased about its pivot axis in a clockwise direction, as seen in Figs. 1 and 2, against the pressure responsive device b-y means of a .helical loading spring 21 which has one. end bearing directly on the intermediate member 23 and its other end bearing on a seat or collar 28. This collar 28 is secured in screw threaded relation on a rod or shaft 29 which in turnis rotatably mounted in the cross portion 20 of the support. Also, the spring seat 28 is provided with a lateral extension or projection which moves in a slot, not shown, in the supporting plate I8 so as to prevent rotation of the member 28 whenthe shaft 29 is turned by meansof asuitable knob 3D on itsy outer end.

'I'hus by turning the knob 3U, the spring seat 28 is moved along the threaded rod 29 thereby to vary as desired the pressure applied by the helical spring 21. n

Thus. movement of the pgin vI3 in response to temperatureV and pressure moves the operating ,arm kI4 about its. pivot and the free end of the voperating arm carries a projection 3I made of insulating material which when moved by the y operating member actuates a flexible spring arm 3.2 carrying the movablecontact I6. This spring gV arm 32 is secured to the supoprt I 'I at its lefthand end at the point 33 which forms an electric terminal for connection of the two contacts in an electric circuit, such as the circuit of the driving motor for the refrigerator. On its other end the arm 32 carries an armature 34 made of magnetic material which cooperates with a small permanent magnet 35 mounted in va recess in the support I1 and held in place by a non-magnetic member 36 secured to the base and having one end extending into a slot across the outer face of the magnet. This magnet is preferably shaped in the form of a disc with a groove (not shown) on its outer side forming two projections which are magnetized as north and south poles. It is made o-f material having a high magnetic coercive force preferably an alloy of aluminum, nickel, copper and iron, such as described and claimed in Patent No. 1,947,274, issued on February 13, 1934, to William E. Ruder, and Patent No. 2,027,997, issued on January 14, 1936, to Tokushiohi Mishima. An alloy consisting of 12 per cent aluminum, 25 per cent nickel, and 5 per cent copper, by weight, the balance being iron, is suitable.

The spring arm 32 is strong enough and is biased to pull the armature 34 away from the magnet and thereby move the contact I6 into engagement with the other contact. As seen in Figs. 1, 2 and 4, the armature is held in engagement with the magnet by the insulating pin 3| bearing against the arm 32. Upon an increase in temperature, the pin I3 on the pressure responsive device moves downward and moves the arm I4 counterclockwise, as seen in Figs. 1 and 2, whereby the arm 32 is released and pulls the armature away from the magnet. Conversely, when the arm I4 is moved back clockwise by the spring 21 upon a decrease in pressure to the position seen in Figs. 1 and 2, the arm 32 is first bent upward slowly by the pin 3| until the armature reaches a predetermined position near the magnet when the magnet snaps the armature to its attracted position and separates the contacts with a snap action. The stationary contact I5 is mounted on a spring arm 31 secured to the base I1 at 38 where an electric connection with the vcontact l5 can be made. When the contact I6 engages the other contact,

the spring 31 bends downward somewhat to give v.

a wiping action, and when the pin 3| moves the arm 32 upward to separate the contacts, the arm 31 straightens and thereby maintains the contact I5 in engagement With the other contact until the contact I6 is snapped to its attracted position.

The mechanism is enclosed in a casing 38a made of a suitable electrically insulating material, preferably a molded compound.

In addition to the adjustment of the strengthy of the spring 21 by turning the knob 30 whereby the normal operating temperature of the refrigerator can be changed, I provide also a second adjustment of the spring 21 which is made by means of a cam projection 39 on the knob 30, which projection engages one end of a bell crank lever 4D pivotally mounted on a pin 4I secured to the two supporting plates I8 and I9. This bell crank lever has another arm 42 which extends out to the outer right-hand end of the intermediate member 23 and is there secured to the intermediate member by means of a screw 43. When the knob 3D is turned far enough in a counterclockwise direction, which also moves the spring seat 28 upward to compress the spring 21, the cam 39 engages the bell crank 40 and moves it counterclockwise from the position of Fig. 1 to the position of Fig. 2. This tilts the intermediate member 23 clockwise about its left-hand end, which bears on the operating arm I4, to the position shown in Fig. 2. In this position of the intermediate member 23, it will be observed that the spring pressure is applied to the operating arm I4 at this point of engagement with the left-hand end of the intermediate member 23. Consequently, the operating arm serves as a lever for the spring pressure with respect to the pin I3 which bears on the operating arm at a point between its pivot 25, 26 and the left-hand end of the intermediate member 23. As a result, when this adjustment is made. the spring has a leverage advantage and a much greater pressure must be applied to the pin I3 to move the operating arm I4 and close the contacts. As applied to a refrigerator, the circuit of the driving motor is thus kept open and the driving motor deenergized until the temperature in the refrigerator has increased to a higher value sufficient to defrost the refrigerator.

To facilitate the slight amount of pivotal movement between the lever 42 and the member 23, an extruded ridge 44 is formed in the member 42 underneath the head of the screw 43. Also, the bell crank 40 is provided with an arm 40a which serves as a stop for the lefthand end of the arm I4, as seen in the drawing, when the arm I4 is moved to engage the contacts I5 and I6 under defrost conditions, shown in Fig. 2.

In order to secure the member 23 in a fixed position relative to the operating arm I4 while providing for tilting of the member 23, a thin flexible metal strip 45 is provided between the two parts. The ends of this strip are secured respectively to the arm I4 and the member 23, as by electric spot welding. This strip thus definitely fixes the pivot point of the member 23 on the arm I4 when the member is tilted.

Also, to secure the operating arm I4 immovably, except for pivoting, with respect to the supporting brackets I3 and I9, a second thin metal flexible plate 46 is provided adjacent the pivoted end of the arm I4. This plate has its left-hand end, as seen in Figs. 1 and 2, secured to the arm I4 as by electric spot welding. Its other or right-hand end has a tab or projection 41 at each side (only one of which is shown) and bent at right angles to the other portion of the plate 46 and in parallel relation with the brackets I8 and I9. These tabs are secured to the brackets respectively, as by spot welding. Thus when the arm I4 is pivoted on its bearings 25 and 26, the plate 43 bends to provide for this pivotal movement.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure bv Letters Patent of the United states, is:

l1. A control device comprising an arm provided with a pivot, an operating device engaging said arm a predetermined distance from said pivot, a spring for applying a force to said arm in opposition to said operating device, a member between said spring and said arm. and means for tilting said member on said arm thereby to apply the force of said spring to said arm at the point of pivotal engagement of said member with said arm.

2. A control device comprising an arm provided with a pivot, an operating device engaging said arm a predetermined distance from said pivot, an intermediate member normally lying in lengthwise engagement with said arm, a spring engaging said member so as to apply a force to'said arm in opposition to said operating device, and means for tilting said member on said arm so that one end of said member pivotally bears on said arm thereby to apply the force of said spring to said arm at the point of pivotal engagement of said member with said arm.

3. A control device comprising an arm provided with a pivot, an operating device engaging said `arm a predetermined distance from said pivot, an intermediate member normally lying in lengthwise engagement with said arm, a spring opposing said operating device engaging said member so as to apply a force to said arm in opposition to said operating device, and means for moving one end of said member away from said arm with the other end of said member pivotally bearing on said arm thereby to apply the force of said spring to said arm at the point of pivotal engagement of said member with said arm.

4. A control device comprising an arm provided with a pivot, a fluid pressure responsive device engaging said arm a predetermined distance from said pivot, an intermediate member having one end engaging said arm at a point which is av greater distance from said pivot than said predetermined distance, Said member normally lying in lengthwise engagement with said farm, a spring opposing said pressure responsive device engaging said member so as to apply a force to said arm, and means for moving said member Aabout said end as a pivot away from said ,arm so that the force of said spring is applied to said arm at said point, and circuit controlling means operated by said arm.

5. A control device comprising an arm provided with a pivot, electric switching means operated by said arm, operating means engaging said arm a predetermined distance from said pivot, an intermediate member normally in engagement with said arm, a spring opposing said operating means engaging said intermediate member so as to apply a force to said arm in opposition to said operating means, and means for tilting said intermediate member on said arm so that the force of said spring is applied to said .arm at the pointr of engagement of saidgintermediate member and said arm.

6. A control device comprising an arm provided with a pivot, electric switching means operated by said arm, operating means engaging said arm a predetermined distance from said pivot, an intermediate member normally in engagement with said arm, a spring opposing said operating means engaging said intermediate member so as to apply a force to said arm in opposition to said temperature responsive device, an operating member having one end connected to said intermediate member, and cam means movable into engagement with said operating member thereby to tilt said intermediate member on said arm so that the force of said spring is applied to said arm at the point of engagement of said intermediate member with said arm.

7. A control device for refrigerators comprising an arm provided with a pivot, electric switching means operated by said arm, a temperature responsive device engaging said arm a predetermined distance from said pivot, an intermediate member normally lying in lengthwise engagement with said arm, a spring opposing said pressure responsive device engaging said member so as to apply a force to said arm in opposition to said temperature responsive device, a rotatably mounted knob rotatable to vary the force applied by said spring to said arm, a pivoted operating member having one end connected to one end of said intermediate member, and a cam on said knob movable upon rotation of said knob into engagement with the other end of said operating member thereby to move said end or said intermediate member away from said arm so that the force of said spring is applied to said arm at the point of engagement of the other end of said intermediate member with said arm.

8. A control device comprising a support provided with substantially parallel supporting members, an arm pivotally mounted on said members between said members, a flexible metal member having its ends respectively secured to said arm and said brackets at points adjacent the pvot of said arm thereby to secure said arm in a predetermined position with respect to said brackets while providing for pivotal movement of said .arm on said brackets, an operating device engaging said arm a predetermined distance from said pivot, a spring for applying a force to said arm in opposition to said operating device, a member between said spring and said operating arm, means for tilting said member on said operating arm so as to change the point of application or said force to said arm, and a flexible metal member between said rst member and said armhaving its ends secured respectively to said iirst member and said -arm so as to x the pivot point of said member on said arm when said member is tilted.

9. A control device comprising an arm provided with a pivot, an operating device engaging said arm a predetermined distance from said pivot, a member engaging said arm, a spring bearing on said member thereby to apply a force to said arm a predetermined distance from said pivot in opposition to said operating device, and means for moving said member with relation to said arm so as to apply the force of said spring to said arm through said member at a different distance from said pivot.

. EDGAR H. AYERS. 

